Antioxidant enzyme activity in human stratum corneum shows seasonal variation with an age-dependent recovery.

The stratum corneum, as the body's principal barrier to the environment, is continuously exposed to environmental sources of reactive oxygen species like ultraviolet light, ozone, and pollution. Reactive oxygen species are believed to be involved in cancer, aging, and inflammatory skin disorders. We have developed a method to measure catalase and superoxide dismutase activity on tape strippings from the human stratum corneum and demonstrated a gradient of antioxidant enzyme activity across the stratum corneum with decreasing levels towards the skin surface.

Age-dependent response of energy metabolism of human skin to UVA exposure: an in vivo study by 31P nuclear magnetic resonance spectroscopy.

Purpose: The aim of our study was to evaluate the in vivo energy metabolism of human skin as a function of age, in conditions of rest and after a mild stress caused by a suberythemal UVA irradiation.

Methods: The kinetics of UVA-induced modifications in high-energy phosphorylated metabolites of young and old skins were non-invasively monitored over a period of 24 h using 31P nuclear magnetic resonance spectroscopy. In vivo 31P spectra were obtained on the ventral aspect of the wrist, using a NMR Imaging Spectrometer equipped with a double-tuned surface coil.